This is the closest I could find. http://www.scca.com/Club/Index.asp?IdS=0FC065-823FBE0&x=030|057&~=
"9.3.26. FUEL CELL SPECIFICATIONS
All cars must be equipped with a safety fuel cell complying with these
specifications, except for Showroom Stock, Touring, Spec Miata, and
Improved Touring. All safety fuel cells shall be constructed and certified in
accordance with the FIA FT-3 or higher (FT-3.5, FT-5, etc.) specifications.
All safety fuel cells shall consist of a foam-filled fuel bladder enclosed in
a metal container at minimum. "